An element forms an oxide A₂O₃ which is acidic in nature. Identify A as a metal or non-metal.

A non-metal X exists in two different forms Y and Z. Y is the hardest natural substance, whereas Z is a good conductor of electricity. Identify X, Y and Z.

By which method metals of high reactivity are purified?

List two properties of gold and silver which make them most suitable for making ornaments according to our need.

Why does calcium float on water?